THE INSTITUTE FOR CANCER RESEARCH 
7701 BT1BHOLME AVENUE 
FOX CHASE • PHI LlDtLPHIA, PEN NSYLVAN I A lOlll 
(£15) 042 - lOOO • CABLE ADDRESS'- CAN6EARCH 
BARUCH S BLUMBERG. M D . PH D 
ASSOCIATE DIRECTOR FOR CLINICAL RESEARCH 
213/728-2203 
January 4, 1980 
Dr. Donald S. Fredrickson 
Director 
National Institutes of Health 
Bethesda, Maryland 20014 
Dear Dr. Fredrickson: 
I write to tell you that I support your position that 
recombinant DNA research performed with the _E. coli strain 
K12 should be classified as P1/EK1. I understand that the 
experience with this strain indicates that its hazardous 
potential is low and that it, therefore, can be reclassified. 
The regulations for the control of recombinant DNA research 
it appears, will serve as an example of appropriate self-regulation 
by the scientific community. It, therefore, should have built 
within it the flexibility to respond to new information. Your 
action in changing the classification is an indication of this. 
With kind personal regards, 
Sincerely yours 
BSB: ja 
[641] 
THE FOX CHASE CANCER CENTER 
